Process of coking hydrocarbon material and coke oven for practicing said process



Feb. 4, 1936. A. H. GALLAHER PROCESS yOF COKING HYDROCARBON MATERIAL AND COKE OVEN FOR PRACTICING SAID PROCESS Filed April 22, 1930 /lav ATTORNEY Patented Feb. 4, 1936 UNITED STATES 2,029,865 PROCESS oF como HypnocAnBoN MA- TERIAL AND COKE ING SAID PROCESS OVEN FOB. PRACTIC- Alvan Harlan Gallaher, Plainiield, N. J., assignor to The Barrett Company, New York, N. Y., a. corporation of New Jersey Application April 22, 1930, Serial No. 446,234

12 Claims.

This invention relates to coking hydrocarbon materials, which are liquefied or liqueiiable by heat, and more particularly to a process of coking coal tar pitch in an oven of the beehive type.

From one aspect this invention may be considered as an improvement on the invention of the Hall Patent No. 1,650,126, November 22, 1927, which discloses a process for the manufacture of metallurgical coke involving the coking of coal tar pitch in an oven of the beehive type. 'I'he invention also comprehends ovens of the beehive type suitable for practicing this process.

One object of this invention is to provide a process for coking coal tar or other pitch or hydrocarbon material which more effectively utilizes the available heat of the material to coke it and which permits operation at higher average temperatures in the oven so that the time of coking is decreased. Another object is to over- 20 come the foaming and boiling over difliculties usually encountered in coking coal tar pitch and other hydrocarbon material. Heretofore in coking coal tar pitch and other liquid hydrocarbon materials to avoid foaming and boiling over of the charge, the amount of material introduced into the oven was materially less than the capacity thereof, thereby providing a substantial free space, usually 2 feet or more, above the top of the charge and below the gas flue in the side of the oven, in which space the foam could rise and collect and would therefore not be lost to the system. In accordance with the process of this invention, foamings materially reduced, if not substantially eliminated, so that the capacity of the oven can more effectively be utilized Without involving loss of product. Accordingly, this invention increases the coke-making capacity of the oven, as it permits handling of larger charges. Still another object is to provide an oven of the beehive type in which coal tar pitch or other liquid hydrocarbon materials may be charged and coked in the manner above indicated, so that foaming of the-charge is substantially retarded, if not eliminated, and the available heat content of the pitch is eiiciently utilized to coke it. Other objects and advantages will appear from the following detailed description.

The aforementioned Hall patent discloses the coking of coal tar pitch involving the charging of the pitch into an oven of the well known beehive type, which is circular in horizontal cross section, or into a beehive oven of the Belgian type, which is somewhaty rectangular in cross section. The side walls and floor of these ovens were built up of rebrick throughout. An open- (Cl. 202-6l ing may be provided in the top for charging the oven or as an outlet for products of combustion, and an opening may be formed in the side near the oor for withdrawal of the coke when the beehiving is completed. This opening is bricked up during the coking operation in order to retain the molten pitch. A hole may be left in this brickwork near the top to admit combustion air for the coking; the amount of air admitted may be controlled by varying the effective size of this hole, as by partially blocking it with loose bricks. Such ovens may also be provided with an opening near the top for leading the products of combustion to a chimney flue or to a waste-heat boiler. Beneath the rebrick oor of such ovens a layer of sand was positioned which rested on a layer of clay in turn supported by the sub-foundation of concrete. The above described beehive ovens are well known and are of the type frequently used for coking coal. In accordance with Halls invention, coal tar pitch was charged in such oven, preferably having a temperature of approximately 1100 F. from a previous run, combustion of the volatile constituents of` the pitch taking place upon charging, and the heat generated by burning the volatiles was utilized to coke first the top portion of the charge, coking taking place gradually downward through the mass of pitch in the oven. 'I'his process resulted in the formation of a superior metallurgical coke, the chemical composition and the physical properties of which are given in the specification of the Hall patent.

Upon charging a fresh charge of pitch into an oven it was found that foaming and boiling of the pitch takes place, and to avoid loss of product it was considered necessary to charge the pitch rather slowly and.charge only so much pitch to each oven that boiling over through the opening at the top or through the gas oitake flue at the side with consequent loss of pitch and product, would not take place. Hence for eciently coking pitch in the usual beehive oven, the full capacity of each oven could not be utilized.

I have found that the layer of sand, clay and concrete, particularly the sand and clay layers beneath the ,Xoor of the oven, act as heat reservoirs or storage chambers during the coking operation, the high temperatures of 1100 to 2200* F. and above prevailing in the oven, causing the heat to flow through the oor into the sand and clay layers beneath, resulting in a considerable loss of heat and the storage of heat in the layers beneath the floor. Upon the placing of a fresh charge, which is at a relatively low tem- 55 perature, in the coke oven, owing to the temperature difference between the charge and the temperatures prevailing in the sand and clay layers beneath the floor, a rush of heat through the floor occurs into the bottom and lower portion of the charge. While the passage of heat into the base portion of a coal charge is not obv jectionable and, in fact, is in many cases desired, the flow of heat into the base of a charge of pitch or other liquid hydrocarbon materials being coked is highly objectionable. Flow of heat into the base of a mass of pitch, I have found, causes foaming and boiling over of the pitch charge and interferes with the eicient coking of the pitch, which, as pointed out in the Hall patent, is preferably eiected by coking from the top downward, the radiant heat from the oven vault playing a large part in the process.

In accordance with this invention, ovens of the beehive type, beneath the usual rebrick floors .are provided with a. layer of high temperature heat insulating or non-heat-conducting material such as diatomaceous earth in the form of brick, powder, or hollow tile, or other high temperature heat insulating substances such as the commercialproduct sold under the trade name Sil-o-cel (infusorial earth especially selected for its heat insulating properties) which have a heat conductivity materially less than that of sand, clay or rebrick. This insulating layer, I have found, materially impedes and retards the ow of heat through the coke oven floor, and thus prevents the foundation beneath the floor from functioning as a heat reservoir or storage chamber. Upon the placement of a fresh charge in the oven the rush of heat into the base of the charge is thus minimized and substantially prevented, and the rate of flow of whatever heat may pass through the floor into the charge is materially reduced due to the non-heat conducting properties of the layer beneath the floor. Consequently boiling over or foaming of the charge,

if not completely eliminated, is retarded to such an extent that a substantially increased portion of the oven may be utilized and eflicient coking of the pitch takes place.

In the accompanying drawing forming a part of this specification and showing for purposes of exemplication a preferred form and manner in which the invention may be embodied and practiced without limiting the claimed invention to such illustrative instance, Fig. 1 is a fragmentary vertical section, taken on a vertical plane passing through substantially the mid-portion of the oven and illustrating a preferred form of beehive oven for practicing my invention; and Fig. 2 is a. corresponding fragmentary sectional view illustrating a modified form of oven.

The beehive oven, shown in the drawing, is of the well-known type which' is circular in horizontal cross section, and for convenience the present description will be conned to this embodiment of the invention. The improved construction of my invention is, however, capable of other applications, for example to beehive ovens of the Belgian type and to ovens for coking liquid hydrocarbon material in general. Consequently the invention is not confined in its scope to the specic use and embodiment herein described as an illustrative example.

The drawing depictsa beehive oven of interior cylindro-hemispher'rcal shape having a oor I, sides 2 and dome 3 built up of fire-clay or silica brick such as commonly used in beehive or other coking ovens. These brick have, for example, a.

heat conductivity constant based on C. G. S. units of about .0039 and .0042 respectively (according to page 250 of Porter on Coal Carbonization, published by The Chemical Catalog Company, Inc., 1924). The top of the oven is formed with an opening 4 lined with silica brick or firebrlck. The charge may be placed in the oven through this opening. The forward side of the oven near the base thereof is formed with an opening 5 closed by brickwork during coking through a hole in which air may be admitted during the beehive operation. The air flow may' be controlled by more or less closing this hole with loose bricks. The coke may be withdrawn from the oven through the opening 5 after removing the brick-Work therein. The rear of the oven is formed with an aperture B communicating with the rebrick or silica brick lined conduit 'I leading to a ue 8 which may communicate with a waste-heat boiler or chimney (not shown). A damper 9, operable through slot I0 in the superstructure of the oven is provided for regulating and controlling the ow through flue 1.

The exterior of the oven, as usual, is preferably built up of either re or silica brick, as indicated at II, and a clay fill indicated by the reference numeral I2 is provided over the dome portion 3 of the oven between the exterior I I and the rebrick lining for the opening 4, so that the top of the oven structure lies in a horizontal plane.

In accordance with this invention, directly below the level firebrick floor I there is positioned a layer I of high temperature heat-insulating material. For an oven of a diameter of approximately 121/2 feet and interior altitude, i. e.. distance between top point of dome and the floor, of approximately 8 feet, the rebrick floor I may be and preferably is approximately 41/ inches thick.

The heat-insulating material may be diatomaceous earth in the form of brick, powder, or holloW tile, or similar silicious heat-insulating material such as infusorial earth, or shredded asbestos or any substance which has a low heat conductivity, materially less than that of firebrick, sand or clay at the high temperatures prevailing in the base of the oven during coking. Preferably for an oven having the dimensions above indicated the layer I4 is approximately 4 inches thick. The diatomaceous earth brick which in practice has been found admirably suited for the formation of the heat-insulating layer beneath the floor of the oven, has a conductivity constant of approximately one-third to onetwentieth that of rebrick at the temperatures encountered during coking; e. g., about 0.0002 (C. G. S. units).

The high temperature non-heat-conducting layer I@ preferably rests on a layer of clay I5 approximately 4 inches thick, which in turn is supported by the sub-foundation I6 of concrete. The sub-foundation or mat I6 is approximately 24 inches thick and supports the oven structure and superstructure above.

The layer I4 of the modification shown in Fig. 2 is built up of hollow tile 20 vlaid in staggered relation as shown on the drawing. Spaces 2| are thus formed which, it will be noted, are of substantial size as compared with the microscopic spaces found in a layer made up of powdered or brick heat-insulating material. The use of hollow tile under certain temperature conditions and with certain pitches results in a layer of improved heat-insulating properties as contrasted with powdered or solid brick insulating materials.

This may be attributed to the fact that certain pitches have a tendency to seep through the firebrick lining, the pitch seeping through the lining, coking in the interstices of the heat-insulating layer and in time forming a solid coke deposit from top to bottom of the insulating layer. 'This coke deposit deleteriously affects the heat-insulating properties of the layer Il. With hollow tile, the pitch that seeps through cokes in the air spaces 2l, does not form a substantially continuous coke deposit from top to bottom of the heatinsulating layer during the eiective life of the oven and accordingly does not seriously interfere with the heat-insulating properties thereof.

In carrying out this invention the oven preferably having a temperature of approximately 900 to 1100 F. from a previous run is charged with pitch or other liquid hydrocarbon material,

l and combustion of the volatile constituents of the pitch is immediately initiated upon the placing of the charge in the oven. The draft of air entering the oven through opening 5 is regulated so that the temperature does not rise above l400 F. until the coking of the pitch is well under way, after which the temperature may be permitted to rise to approximately 2200 F. Heat from the coking operation is supplied by the combustion of volatile matter that is given off from the pitch or other material placed on the floor of the oven. The heat is applied to the material both by convection from theproducts of combustion and by radiation from the inner surface of the walls and roof or dome o f the oven. During the coking operation volatile constituents pass out through the opening 4 in the top of the oven forming a flame, which flame ceases when a suicient amount of volatile matter has been driven off, thus indicating that the supply of air should be diminished to prevent combustion of too large a portion of the pitch or coke. It has been found that coking begins along the top layer or surface `of the pitch and then progressively downward through the mass of pitch in the oven. With coal tar pitch of the melting point of about 250 F. to 450 F. containirg from 25 to 50% volatile matter, the coking operation requires about 40 hours to about 80 hours with charges of 5 tons to 7.5 tons of pitch when coking in a beehive oven constructed in accordance with my invention of about 12 feet 6 inches diameter.

'I'he following is given as a specific illustration of this invention without intending to restrict the scope of the invention thereto: A charge of approximately 6.65 tons of coal tar pitch having a melting point of 400 F. was charged into t. beehive oven of l2 feet 6 inches diameter, the temperature of the oven being approximately 900 F.

Substantially the entire coking capacity of the oven was utilized as it was found that little or no foaming or boiling over of the pitch took place while it was charged into the oven or during the coking of the pitch. The pitch contained about 40% of volatile combustible material and a fixed carbon content of about 60%. Combustion of the volatile constituents of the pitch was regulated by controlling the inlet of air into the oven so that the temperature within the oven rose to 1800 F. during the beehiving of the charge.` The coking time was about 44 hours after which the coke was quenched by a stream of water while still in the oven, and then the brickwork in the opening 5 was removed and the coke withdrawn. The coke thus obtained had substantially the same'physical properties and chemical composition as the coke disclosed on page 2, lines 66-'73 and 85-99 of the specication of the Hall patent.

This invention materially reduces, if not entirely preventing, the foaming and boiling over of the pitch, encountered in other processes of coking pitch, permits the coking of pitch in the oven utilizing substantially the entire' capacity of the oven or of higher coking temperatures so that the coking time is reduced. Also the invention reduces the loss of heat through the floor of the oven occurring in prior practice and beneficially utilizes the available heat of the pitch for coking it.

I claim:

1. A process of coking a mass of cokable hydrocarbon material which is liquid or liqueiiable by heat, which comprises introducing the hydrocarbon material into a hot coke oven heated by the coking of a previous charge, supplying the heat for coking the hydrocarbon material first to' the upper portion of the mass while impeding the flow of heat from the base of the oven into the lower portion of the mass, and then supplying heat to the mass progressively downward to coke the material progressively downward.

2. A process of coking coal tar pitch in a beehive oven, which comprises charging the pitch into the oven which has been heated by the coking of a previous charge and supplying the heat for coking first to the upper portion of the pitch while minimizing the flow of heat to the lower portion of the pitch,'and then supplying heat to the pitch progressively downward `therethrough to coke the material progressively downward.

3. A process of producing coke which involves charging an oven which has been heated by the coking of a previous charge with cokable hydrocarbon material, initiating within the oven combustion of the volatile constituents of the hydrocarbon material, and supplying the heat thus generated to the upper portion of the mass of material in the oven to coke the material while preventing the flow of heat into the lower portion of the mass of material in the oven through the floor thereof.

4. A process of coking coal tar pitch, which involves charging a beehive oven with the pitch, initiating within the oven combustion of the volatile constituents of the pitch, supplying the heat thus generated rst to the upper portion of the pitch and then progressively downward therethrough to coke the material progressively downward therethrough, and simultaneously impeding the flow of heat into the lower portion of the pitch and the flow of heat from the interior of the oven out through the floor of the oven.

5. A process of coking cokable hydrocarbon material which is liquid or liqueable by heat which involves charging said material into a hot oven of the beehive type having a layer of high temperature non-heat-conducting substance beneath and contiguous to the floor thereof for impeding the flow of heat into the base portion of the material charged into said oven, and supplying the heat necessary to coke said material by burning within said oven the volatile constituents of said material thus coking said material.

6. A process of coking coal tar pitch which involves charging said pitch into a hot oven of the beehive type having a layer of heat insulating substance beneath and contiguous to the oor of said oven, thus impeding the ow of heat into the base of the pitch mass charged into said oven, and supplying the heat necessary to coke said pitch by burning within said oven the volatile constituents of said pitch thus coking said pitch.

7. A process of coking coal tar pitch which involves charging said pitch into a hot oven of the beehive type having a layer of diatomaceous earth beneath and contiguous to the floor of said oven, thus impeding the ow of heat into the base portion of the pitch maas in said oven and the flow of heat through the oor of the oven, and

supplying the heat necessary to coke said pitch by burning within said oven the volatile constituents of said pitch thus coking said pitch.

8. A process of coking coal tar pitch which involves charging said pitch into a hot oven of the beehive type having a layer of diatomaceous earth beneath and contiguous to the rebrick ioor of said oven, thus impeding the iow of heat into the base portion of said mass into said oven, and the fiow of heat through the oor of said oven, and supplying the heat necessary to coke said pitch first to the upper portion of the mass and then progressively downward therethrough thus coking said pitch progressively downward therethrough.

9. A beehive coke oven adapted for the coking,

of coal tar pitch, said oven having a substantially solid foundation beneath the oor of the oven,

aoaaeeo oi" coal tar pitch, said oven having a oor of firebrick, -a substantially solid foundation beneath the re brick iioor, said foundation being devoid of heating iiues and comprising a layer of high temperature heat insulating material of a heatconductivity substantially less than that of the re brick of the ioor disposed beneath the entire extent of the oor of the oven contiguous thereto to prevent the back ow of heat into a fresh charge placed into a hot oven.

11. A beehive coke oven as claimed in claim 10 in which the layer of high temperature heat insulating material is constituted of diatomaceous earth.

12. A beehive coke oven as claimed in claim 10 in which the layer of high temperature heat insulating material is constituted of diatomaceous earth hollow tiles.

ALVAN HARLAN GAlLAI-IER. 

